Not all minerals from nuts can be absorbed by the body

The research team not only determined the total content of elements in the food, but also simulated the processes of gastric and intestinal digestion in a laboratory setting.

The scientists focused on four minerals that are essential for good health. Copper is necessary for the formation of red blood cells, energy production, and the maintenance of the immune system. Magnesium is crucial for bone health and muscle function. Manganese has antioxidant properties and is involved in the formation of bones and connective tissue. Zinc is essential for the immune system, wound healing, and protein synthesis.

First, the total content of these minerals in the nut samples was determined. Then, their bioavailability was assessed using in vitro laboratory modeling of gastrointestinal digestion. This approach is important because the total amount of a nutrient in a food does not always correspond to what the body actually absorbs.

The researchers emphasized the difference between the two concepts. Bioavailability refers to the fraction of a substance that is not only released but also absorbed by the body, taking into account distribution, metabolism, and excretion. To assess it, human or animal studies are required, which requires significant resources and approval from an ethics committee. In turn, bioavailability in a broad sense (in vitro bioavailability or release bioavailability) is the proportion of a mineral that is released from a food matrix in the gastrointestinal tract and is potentially available for absorption. It can be assessed in a laboratory.

In the experiment, the conditions of the human digestive system were replicated: temperature, stirring, pH level and enzymatic composition were controlled. The data obtained was compared with the recommended daily intake of minerals.
After modeling the digestive process, the following was found. In cashews, 56% of copper and 52% of magnesium were available for absorption. The content of manganese and zinc was below the detection limit of the method used. In Brazil nuts, the bioavailability was 50% for copper and 28% for magnesium. Manganese and zinc could not be reliably measured after the test.

Thus, although the nuts under analysis contain significant amounts of copper, magnesium, manganese, and zinc, the body can only absorb a portion of these elements.

According to the researchers, assessing the nutritional value of foods should not be limited to measuring the total content of nutrients. It is also important to study how these elements behave under conditions that mimic the digestive system to accurately evaluate their actual availability to the body. The nuts under analysis should not be considered as the sole source of these minerals. However, they can be a beneficial addition to a balanced and diverse diet.